Apparatus for portioning liquid metal

ABSTRACT

An apparatus for portioning liquid metal from a holding apparatus using pressure gas to force metal therefrom into a mould. Includes a valve housing to be mounted in an opening in the bottom portion of a pouring container which during operation is submerged in the liquid metal of the holding furnace and provided with a pouring tube and gas supply means. The upper portion of the valve housing extends through the opening with sufficient play or clearance to permit the valve housing to be tilted in relation to a vertical when being inserted into the opening, and the valve housing is provided with an outer, upwardly narrowing, generally conical flange having a contact surface area intended to contact a generally conically shaped seating area at the opening in the bottom portion of the container. The housing is pivoted to a lever adapted to force the contact area of the flange against the seating area at the inlet opening.

United States Patent Heimdal et a1.

[451 Dec. 30, 1975 1 1 APPARATUS FOR PORTIONING LIQUID METAL [75]Inventors: lvar Dagfinn Heimdal; Ivar Skreosen, both of Porsgrunn,Norway [73] Assignee: Norsk Hydro A.S., Oslo, Norway [22] Filed: Oct.21, 1974 [21] Appl. No.: 516,871

[30] Foreign Application Priority Data 760,189 10/1956 United Kingdom164/314 Primary Examiner-Allen N. Knowles Assistant Examiner-David A.Scherbel Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [57] ABSTRACTAn apparatus for portioning liquid metal from a holding apparatus usingpressure gas to force metal therefrom into a mould. Includes a valvehousing to be mounted in an opening in the bottom portion of a pouringcontainer which during operation is submerged in the liquid metal of theholding furnace and provided with a pouring tube and gas supply means.The upper portion of the valve housing extends through the opening withsufficient play or clearance to permit the valve housing to be tilted inrelation to a vertical when being inserted into the opening, and thevalve housing is provided with an outer, upwardly narrowing, generallyconical flange having a contact surface area intended to contact agenerally conically shaped seating area at the opening in the bottomportion of the container. The housing is pivoted to a lever adapted toforce the contact area of the flange against the seating area at theinlet opening.

5 Claims, 4 Drawing Figures U.S. Patsnt Dec.30, 1975 Sheetl0f2 3,929,263

Sheet 2 0f 2 3,929,263

U.S. Patent Dec. 30, 1975 APPARATUS FOR PORTIONING LIQUID METALBACKGROUND OF THE INVENTION This invention relates to an apparatus forpouring pre-determined portions of liquid metal from a reservoir, suchas a holding furnace or the like, into a mould or a die-casting machine.

More particularly the invention relates to a portioning apparatus,preferably intended for portioning molten magnesium, in the form of aportioning container to be submerged into the molten metal, whichcontainer is connected with a device for supplying pressurized gas andis provided with a metal outlet in the form of a pouring tube, thecontainer being provided with removable valve means positioned at thebottom of the container.

The pouring action is effected by means of a preferably inertpressurized gas which is supplied to the pouring container from anexternal pressure source. When the metal is to be forced up from apouring container which is submerged in the melt and has an inletopening in the bottom portion for the supply of molten metal from thereservoir, the gas pressure will of course force the metal from thepouring container back to the reservoir (the holding furnace) if nomeasures are taken to prevent such back-flow. Quite a long time ago itwas proposed to use valves to prevent such back-flow. However, so faruseful results have not been obtained in practice using valves, thelatter being susceptible to functioning defects. After having been inoperation for some time unsatisfactory sealing occurs and, further, theback-flow through the valve opening can vary. Primarily this is due toprecipitation and deposition of non-metallic compounds which adhere tothe steel of the valve ball and the valve seat. Therefore, functioningdefects gradually arise, initially in the form of leakages and finallyby complete seizure of the valve body. This problem particularlyprevails with magnesium.

A natural solution would here be to employ a valve housing and ball unitwhich is readily removable and replaceable so that the valve ball and/orvalve housing can be replaced or cleaned. Incidentally, this has beenproposed previously, cf. German Patent 1,194,104, which discloses theuse of an open valve housing having a lower portion which is screwed onto the upper portion of the valve housing, the housing beingsimultaneously seized in a downward narrowing, conically shaped openingin the bottom portion of the pouring container. However, not even thisarrangement will be satisfactory when used in practice. In adisassembling operation the entire equipment must be removed from theholding furnace resulting in oxidation and fire hazard. Gradually thescrew thread of housing portions will be welded together and on repeatedscrewing-off and screwing-on will be destroyed. Thus, also thispreviously proposed solution has been unsatisfactory when employed inpractice.

Therefore, in the most recent time the development has been mostlyfocused on valveless portioning systems, cf. for instance US. Pat. No.2,846,740 and Norwegian Pat. No. 123,618. This type of apparatus has nomoving parts within the melt and this should therefore ensure continousand stable operation and high portioning accuracy. However, here anotherproblem arises. Without a highly accurate control of the gas pressure ablowout of gas through the valveless tube through which the metal isdrawn into the pouring container can result. To a certain extent thiscan be counteracted by an exact monitoring of the ultimate pressure,which, however, in practice results in operating with pressures so lowthat the pouring rate will be too low.

SUMMARY OF THE INVENTION The invention contemplates providing avalve-controlled pouring apparatus which does not have the disadvantagesassociated with the known apparatus, and it is a primary purpose of theinvention to provide a pouring apparatus where the removal and insertionof the valve means can be carried out while the portioning equipment ismaintained within the holding furnace, without it being necessary toeven move the pouring container or the gas supply tube. In the attemptto solve this problem, a series of difficulties will present themselves.

How should a readily dismountable construction be made which alsoprovides satisfactory sealing, and how should a correct insertion beensured when assembling operations must be effected from the outside?According to the invention there is provided an apparatus where theseapparently conflicting aims are fulfilled. The pouring apparatus of theinvention consists of a pouring container having an inlet valve formolten metal provided in the bottom portion of the container, means forsupplying pressure gas from a source of pressure gas, and a pouring tubewhich is connected to the container to deliver portioned amounts ofmolten metal, for instance to a die-casting machine. The valve meansincludes a preferably cylindrical valve housing the upper portion ofwhich extends through an opening in the bottom portion of the containerwith sufficient play or clearance to permit the valve housing to betilted in relation to the vertical when being inserted into the opening.The valve housing is provided with an outer, upward narrowing, generallyconical flange having a contact area intended to contact a generallyconically shaped seating area at the opening in the bottom portion ofthe container, and the valve housing is pivoted to a lever. The lever isadapted to force the contact area of the flange against the seating areaof the inlet opening when the valve means has been attached to thecontainer.

The combination of the pivoted connection of the valve housing with thelever and the clearance between the upper portion of the valve housingand the inlet opening in the bottom portion of the container makes thevalve means self-centering so that it can be directed into position fromthe outside. This will always provide contact area sealing between theflange of the valve housing and the seating area of the containeropening, which surprisingly provides satisfactory sealing during apressure pouring operation.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and purposes of theapparatus according to the invention will be apparent from the followingdetailed description and appended drawings, wherein a preferredembodiment of the invention is described, and in which:

FIG. 1 shows a section through a holding furnace with the portioningpump inserted therein and the valve means fixed into position.

FIG. 2 shows the holding furnace including equipment viewed from above.

3 FIG. 3 shows a magnified detail of the valve means in a lateral view.

FIG. 4 shows a section through the bottom cover plate of the pouringcontainer the valve means parts disassembled and partially shown insection.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a section through the holdingfurnace and shows the pouring equipment inserted therein with the newvalve means mounted in position. The valve means is designed with anupward open valve housing (FIG. 3 and 4), in which a valve bead, i.e.,steel ball 6, has been provided. The valve ball 6 is maintained inposition by a cotter 7 or the like. The lower portion of a lever 2 isrotatably connected with the valve housing 15, and its upper portionmerges into an elongated shaft which extends above the melt and isfastened to a plate 8 by means of fastening means in the form of a wingnut 9 or the like, the plate 8 being rigidly connected with twosuspension struts 19 which maintain the portioning container, designatedby 5, in the proper depth in the melt.

The lower portion of the lever 2 extends into a groove 21 in the lowerportion of the valve housing, which groove forms the metal inlet to theportioning container. The lever 2 is pivoted to the valve housing 15 bymeans of a pin or bolt 3 which extends through coaxial holes through thelower part of the lever and the walls defining the groove 21. Goodclearance is provided between the bolt 3 and such coaxial holes and asimilar clearance is provided between the walls defining the groove 21and the portion of lever 2 extending therein. In this way a simple andefficient articulated joint is achieved which is operative in allplanes.

The valve housing 15 is shown as being cylindrical and consists of anupper, open portion 16 having a sufficient clearance relative to acorresponding cylindrical portion of the peripheral wall defining theopening 22 in the bottom cover plate of the portioning container, whichplate is designated by 4, to permit the valve housing 15 to be tiltedrelative to the vertical when inserted into the opening 22, i.e.,relative to a normal to the bottom cover plate 4.

The cylindrical valve housing further comprises an upwardly narrowing,conical flange 17 having an outer contact area designed to contact aconically shaped seating area 14 which is formed by the lower portion ofthe wall defining the opening 22 in the bottom cover plate 4.

In the drawing, the contact area of the flange 17 and the seating area14 are shown as being simple conical surfaces. However, it will beappreciated that one or both of these areas can very well bedouble-curved, for instance so as to form part of a sphere.

The conicity or tapering angle of the flange 17, and of the seating areaof the bottom plate, is of importance to ensure a self-centeringinsertion of the valve housing 15. If the angle with the horizontalplane is too small, one will not be able to make the valve housing slipinto position, while, however, too great of an angle will not providesatisfactory sealing when operating with the clearance required to hit"when inserting the valve housing 15 into operating position. It has beenfound in practical tests that the best results are obtained when theangle of conicity of the flange 17 relative to the horizontal plane isfrom about 45 to about 60, corresponding to an angle relative to theaxis of the valve housing of 3045. Even when the valve housing is 4inserted obliquely into the opening 22 in the bottom cover plate 4, itsconical contact surface will make it slip into position.

The lever 2 can be lifted and lowered by means of a handle 11. Thisoperation can readily be performed with one hand. When the valve housing15 is fixed in proper position, lever 2 is moved into position andsecured to the plate 8. The joint at the bolt 3 permits these movements.

As mentioned above, the plate 8 is rigidly connected with two struts 19which maintain the portioning container submerged to a suitable depth inthe melt. The entire portioning equipment including the lever 2 and theplate 8 can be moved back and forth along rack arms designated by 10.

The wing nut 9 need only be tightened manually. Theoretically the upwardpull power serves only to counteract the excess pressure on the valvemeans during portioning plus the weight of the lever 2 and the valvemeans. If the nut 9 is tightened too much, the lever 2 can be strainedtoo much and permanently deformed, which of course is not desirable.Practical tests have shown that the valve provides satisfactory sealingwhen the wing nut 9 is tightened manually. It is important that the pullpower is then acting along the longitudinal axis of the portioningcontainer, so that the valve is pulled towards the center of the opening22 to finally be centered therein.

As shown in FIGS. 3 and 4, the lower portion of the valve housing 15 isconstructed so that there will be ample passage for the metal to flowthrough the valve.

The opening 22 in the bottom cover plate 4 is made wide enough to permitinspection as required on cleaning the interior of the portioningcontainer 5.

The lever 2, which is fastened to the plate 8, is mounted or located soas not to prevent the portioning tube, which has been designated by 13,from being moved as desired during portioning operations. The portioningtube 13 must be adjustable into various sloping angles and must berevolvable to either side. The portioning equipment is so constructedthat the portioning tube 13 can be taken out of the melt without itbeing necessary to move any other part of the equipment.

When the valve means is to be inserted, the lever 2 including the ballvalve is first placed on the rim of the furnace to be preheated. Thelever 2 can then be introduced either on the left-hand side or on theright-hand side of the gas supply tube, which has been designated by 12,and the valve means is inserted under the bottom cover plate 4. Asexplained above, the valve means is self-centered as it slips upwardalong the contact area 14.

The lever is then fastened to the plate 8. After about 5 minutes thelever will be hot and will have acquired maximum length extension. Thewing nut 9 is then tightened manually and the pouring apparatus is readyfor use.

After about 1 week of continual operation the ball valve must berenewed. The valve must be dismounted immediately after being removedfrom the melt. The cotter 7 is pulled out and the ball 6 is decantedthrough the opening 20 before getting stuck due to freezing of the metalresidues in the valve. The bolt 3 is then pulled out and the ball valvecan be replaced by a new valve. The oxidized (oxide coated) ball valveis cleaned by treatment in dilute nitric acid and can be reused.

After a prolonged time of operation also the portion ing container 5must be removed for cleaning and inspection. In the case of the priorart screwed-on valves, the valve body will prevent the metal fromrunning out of the portioning container when the latter is lifted out ofthe melt. Often also the problem of oxide clogging of the inlet of thevalve means arises, and it may be very difficult to drain the container.

Thus a further substantial advantage of the invention is indeed that thedemountable valve means can be removed by simple manipulations and thatthe metal will then drain through the wide opening 22 in the bottomcover plate.

We claim:

1. In an apparatus for portioning liquid metal comprising a portioningcontainer intended to be submerged into a reservoir of molten metal,means for supplying pressure gas to said container and a metal outlettherein to be connected with a mould, such as a die-casting machine,said container being provided with a demountable valve means positionedat a bottom portion thereof to permit liquid metal to flow into saidcontainer when gas pressure is relieved, the improvement wherein: saidvalve means comprises a valve housing having an upper portion whichduring operations extends through an opening in the bottom portion ofsaid container with sufficient clearance to permit the valve housing tobe tilted in relation to a vertical when 6 being inserted into saidopening, said valve housing being provided with an outer, upwardnarrowing, generally conical flange having a contact area intended tocontact a generally conically shaped seating area at said opening in thebottom portion of said container, said valve housing being pivoted to alever.

2. An improved apparatus for portioning liquid metal as claimed in claim1, wherein. the contact area of the flange of said valve housing formsan angle of 30 to 45 with the axis of said valve housing.

3. An improved apparatus for portioning liquid metal as claimed in claim1, wherein said valve housing has a movable valve ball provided therein,is upwardly open, and is provided in its upper portion with areplaceable cotter to prevent said ball from moving out of said valvehousing.

4. An improved apparatus for portioning liquid metal as claimed in claim1, wherein the lower portion of said valve housing is pivoted to saidlever by means of a horizontally disposed bolt which extends with anample clearance through bores provided in said lever and in the walls ofsaid valve housing.

5. An improved apparatus for portioning liquid metal as claimed in claim1, wherein said lever is provided with an upper inwardly bent portionhaving fastening means to fasten said lever along a line runningcentrally through said valve housing.

1. In an apparatus for portioning liquid metal comprising a portioningcontainer intended to be submerged into a reservoir of molten metal,means for supplying pressure gas to said container and a metal outlettherein to be connected with a mould, such as a die-casting machine,said container being provided with a demountAble valve means positionedat a bottom portion thereof to permit liquid metal to flow into saidcontainer when gas pressure is relieved, the improvement wherein: saidvalve means comprises a valve housing having an upper portion whichduring operations extends through an opening in the bottom portion ofsaid container with sufficient clearance to permit the valve housing tobe tilted in relation to a vertical when being inserted into saidopening, said valve housing being provided with an outer, upwardnarrowing, generally conical flange having a contact area intended tocontact a generally conically shaped seating area at said opening in thebottom portion of said container, said valve housing being pivoted to alever.
 2. An improved apparatus for portioning liquid metal as claimedin claim 1, wherein the contact area of the flange of said valve housingforms an angle of 30* to 45* with the axis of said valve housing.
 3. Animproved apparatus for portioning liquid metal as claimed in claim 1,wherein said valve housing has a movable valve ball provided therein, isupwardly open, and is provided in its upper portion with a replaceablecotter to prevent said ball from moving out of said valve housing.
 4. Animproved apparatus for portioning liquid metal as claimed in claim 1,wherein the lower portion of said valve housing is pivoted to said leverby means of a horizontally disposed bolt which extends with an ampleclearance through bores provided in said lever and in the walls of saidvalve housing.
 5. An improved apparatus for portioning liquid metal asclaimed in claim 1, wherein said lever is provided with an upperinwardly bent portion having fastening means to fasten said lever alonga line running centrally through said valve housing.